package TestDemo;

class A {
    String name;
    int age;
}

class B extends A{
    int age2;
}

class C extends B{
    int num;
}

public class Test {
    public static void main(String[] args) {
        A a0 = new A();
        A a1 = new B();
        A a2 = new C();
    }
}
